Engineering innovations to improve irrigation efficiency

Two examples are given of engineering innovations to improve water use efficiency in irrigation. Firstly, water savings are possible for light soils by converting from surface to overhead irrigation practice but the related energy supply needs to be affordable and sustainable. Use of combined wind and solar cell units to power sprinkler or drip systems was examined with two types of pump powered by direct current (DC). A wetted diameter of 1.1similar to2.6 m was possible with the 60 W submersible pump. Tests showed that a 120 W diaphragm pump was capable of producing a 10 1/minute flow with a pressure of 10 m water head. Pumps drew supplies from tanks containing artificial zeolites for water clarification by coagulation. Both arrangements seemed compatible with energy storage using a conventional car battery. Secondly, successful hydraulic regulation of irrigation control gates has considerable benefits. A new means of achieving this uses a regulation plate that is rigidly connected to a float, which is actuated by water levels upstream of a weir in the supply channel. Movement of the regulation plate promotes a steady offtake flow despite large variation in upstream water levels. Corresponding improvements to water distribution efficiency are described for Japanese irrigation networks.